September weather will determine fall leaf colors

Associated Press

Sunday

Aug 26, 2018 at 2:17 PMAug 26, 2018 at 2:30 PM

CULLOWHEE, N.C. (AP) — Hotels and retailers are gearing up for the fall foliage season in the North Carolina mountains, but the brilliance of the show from the changing leaves is still to be determined.

The key to almost every season is the temperatures and amount of sunshine in September, Howard Neufeld, Appalachian State University professor of plant eco-physiology said.

"Fall colors are very dependent on the weather. September is the most crucial month. If we start to get a cooldown, with sunny days and cool nights, those are the best conditions for fall color," Neufeld told the Citizen-Times of Asheville.

The fall tourism season is crucial to western North Carolina. Officials estimate it brings up to $800 million to the state.

And it lasts a long time, thanks to elevations from the eastern United States highest peak, Mount Mitchell, at 6,684 feet (2,037 meters) to areas in the Piedmont closer to 1,000 feet (300 meters) above sea level.

"One of the benefits of looking at color in WNC, we have such a tremendous elevational difference. It's the longest fall color period in the United States. In New England, being farther north and less elevational change, at most it's two weeks. If you miss it at one elevation for some reason, then just go down to a lower elevation and you'll see it the following week," Neufeld said.

Colors in the highest elevations will peak in September, while the lower elevations will see their most vibrant color in early November.

And that September sunshine is also critical to the vibrancy of colors. Plants produce anthocyanins — the same red pigment that colors strawberries and roses — in the early fall if they get enough sunlight for photosynthesis, Neufeld said.

"That's why if it's cloudy and rainy in September and the plants get less light, you don't get a bright red color," he said.

There is one very critical wild card to any fall foliage season in the North Carolina mountains, and that happens hundreds of miles away. A dying hurricane can bring heavy winds and rain into the mountains, stripping leaves and ending the foliage season in one bad day or two.

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